China Mobile recently surpassed 15 million iPhone users despite not officially carrying the device. This is even more impressive considering that the iPhone doesn't yet support China Mobile's 3G (TD-SCDMA) network, so all those users are limited to the carrier's 2G network.
According to a PeopleDaily report, many iPhone 4S owners on China Mobile's network had issues activate their SIM cards and making phone calls with a full signal.
A telecom technology expert explained that technically, the signal problems were caused by iPhone 4S handsets' GSM chips, which only supports the P frequency band (885-915MHZ), but does not support the E frequency band (880-890MHz). As China Mobile's GSM network supports both the P and E frequency bands, iPhone 4S handsets will lose signal or cannot make calls despite having a full signal when they are only covered by the E frequency band which is mainly for indoor use. The phones will regain signal when covered by the P frequency band, which is mainly for outdoor use and the most commonly used band under the standards of the International Telecommunication Union.
China Mobile says Apple has updated iPhone 4S devices manufactured after February 8th to support their 2G network and will offer a software update in early March to address the issue with older devices.
Read More [via TNW]